Book of Genesis

[Genesis 1:1 NKJV]
In the beginning God created the heavens and the earth.
God had "Being" in the beginning, but the heavens and the earth had "Coming into being" in the beginning by God. God did not come into being, but had Being in the beginning; but the heavens and earth had to come into being through getting created by God. He who had Being in the beginning without coming into Being is He who "Was;" but those that had coming into being in the beginning had beginning and therefore were not (was not) in the beginning.
In the beginning, "God was;" but the heaven was not and the earth was not. God was in the beginning, and He was God in the beginning. The word "Was in the beginning" means "Being, Existing or Reality in the beginning." God was, God is, and God is to come: meaning God has Being from everlasting, has Being presently and has Being to everlasting. Hence, God is the "I Am." It's not just "Been" but "Being."
[John 1:1-2] — "In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God."
He was God already before He created the heaven and the earth. The creation did not make He who I Was or who He is; rather He made the Creations what they were and what they shall be. There was no beginning to existence of God but to existence of all things which He created. Behold God had no beginning, but God is the very beginning of the heavens and the earth He created.
The book of Genesis opened with God’s answer and fulfilling the very first challenge of all challenges, and that was the challenge of beginning (creating or starting) all things in the beginning. Imagine having the beginning without beginning. It would have been a wasted beginning if nothing was began or created in it. To un-waste the Beginning, God created the Heavens and the earth. Creating or beginning the Heavens and the Earth was God’s fulfilling and perfecting the Beginning of all things. Knowing Him as the God of Creation may also necessitate knowing Him as God who manages both Resources and Creativity in both time and purpose.